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A class action suit is being brought against Mercedes / Daimler AG due to alleged defects in the M156 V8 motor. The suit states that these defects are due to premature wear. The premature wear taking place as a result of the material used in the camshafts. The camshafts used are made of cast nodular iron. The valve lifters used however are made of 9310 grade steel. In the official complaint it is stated that the combination of these metals as designed is contributing to premature wear of the M156 motors. This can be due to improper heat treating of the metals or improper offset. The main sticking point is that Mercedes and AMG have known about this since 2007 when service bulletin S-B 05.20/20b was released. We will keep you updated on the details as this goes forward.

Just an FYI. I'll likely pick up a 2012 C63 with M156 so I can again own one of the baddest N/A production V8s in the history of the world. It may have it's flaws (all motors due though not to the extent these do) but to me it's also the ultimate V8. Killer 4v heads, great intake manifold and the bore and displacement to not only twist but torque as well.

Does the fact that MB changed the oil spec on these motors have anything to do with this supposed problem?

Changing oil weight effects how quickly a lifter pumps up after a cold start, and also how much compression occurs (more with a lighter weight oil) when the cam lobe depresses the rocker. In OHC engines with lifters anyway. In this case the buckets would compress less or more depending on the weight of oil which would increase or decrease actual valve and duration lift a minute amount, in some cases (non cam on bucket OHCs) more than that.

In this instance and in my opinion and those of many other respected engine builders, oil has nothing to do with the problem. It could neither cause nor resolve the issues created by the above design flaws. Wouldn't matter if you ran 10w-30 vs 0w-50.

More specifically in this case you have an auto manufacturer counting on the ignorance of it's own customers to accept responsibility for an OEM design flaw by placing blame where it doesn't belong. No amount of modding can tear up an engine the same way this design flaw can. Linking the two acts isn't even a far stretch by MB, it's physically impossible, and I sincerely hope they don't get away with it.

It looks like the owner in this case was out of warranty when the failure occured. But he is claiming the damage happened when the new car warranty was in effect. He believes there should have been a recall and wouldn't have had to pay out of pocket for repairs.

I am still under the impression, if you have a factory warranty not worry too much. As long as your car is not modded.

Originally Posted by MHP LLC

Regardless of how I feel I believe there will come a time sooner than later after which we (the automotive aftermarket) will no longer be able to tune cars legally. With the emissions crunch getting worse and the fact that adding just 1 degree of timing advance alters emissions, it's going to be all to easy for the OEMs to cut us out.

That will be a sad day, but it does look like it is heading in that direction. I will say one thing. As I get older, I am more than happy with what is being offered from factory, horsepower wise. Honestly no one needs more than 451hp the C63 offers. I still remember when the E36 M3 had 240hp and everyone thought it was the greatest thing since sliced bread.

Originally Posted by MHP LLC

Just an FYI. I'll likely pick up a 2012 C63 with M156 so I can again own one of the baddest N/A production V8s in the history of the world. It may have it's flaws (all motors due though not to the extent these do) but to me it's also the ultimate V8. Killer 4v heads, great intake manifold and the bore and displacement to not only twist but torque as well.

If these cams are getting scored and ground so severely wouldn't there be evidence of excessive metal shavings in the oik and oil filters? Wouldn't that be a red flag? I would assume an MB service department would look for that type of stuff. These dealerships ae hurting for work just like the rest of the economy why not point out an issue to try to either drum up some warranty revenue or get the customer to cough up some loot?

I honestly believe Benz, BMW, Audi or any brand should be allowed to deny warranty work if the engine has mods. You want your warranty intact, leave your prowertrain stock.

No offense, but this is a horrible line of thinking. They want this though, they want people to just roll over. No engine mods? Oh, so they should deny my transmission warranty due to an aftermarket filter? What about a bad piston due to a muffler? Come on.

If these cams are getting scored and ground so severely wouldn't there be evidence of excessive metal shavings in the oik and oil filters? Wouldn't that be a red flag? I would assume an MB service department would look for that type of stuff. These dealerships ae hurting for work just like the rest of the economy why not point out an issue to try to either drum up some warranty revenue or get the customer to cough up some loot?

You will see evidence of metal (what used to be camshaft) on top of the heads, sometimes it works its way down between the valves/seats and that's bad for many obvious reasons.

How often does any MB dealer have the valvecovers off a M156? Never unless there is a non related internal issue that forces them to go in.

If dealers know MB won't reimburse them for warranty work for this issue then they are more inclined to ignore it as well.

Like yomomma said, harder cams (not necessarily larger but harder) and/or performing regular visual inspections of the cams/buckets which isn't exactly the easiest thing in the world to do. However there are no other ways.

It looks like the owner in this case was out of warranty when the failure occured. But he is claiming the damage happened when the new car warranty was in effect. He believes there should have been a recall and wouldn't have had to pay out of pocket for repairs.

He may have been out of warranty when the issue crippled the car, but if the issue started and festered under warranty it should be covered even if he is out. I believe he is correct in his thinking regarding a recall. It's all a decision based on $ as previously stated. MB did the math and concluded it was cheaper to try and skirt the issue than perform a recall on all M156s.

That will be a sad day, but it does look like it is heading in that direction. I will say one thing. As I get older, I am more than happy with what is being offered from factory, horsepower wise. Honestly no one needs more than 451hp the C63 offers. I still remember when the E36 M3 had 240hp and everyone thought it was the greatest thing since sliced bread.

I hope I never get old (jk). I'm still going up the hill whereas I keep getting used to the power and wanting more like a lot of performance enthusiasts. Too much is never enough. A tune only C63 will serve 95% of owners nicely, stock unless P31 they are so handicapped it's not fair. You just have to uncork them, even if it is just software.

The only car you'll find the M156 in post MY 2012 is the C63 and that's just for one more calendar year then it switches as well.

Second, I've read that the new 5.5TT will simply not fit (read: cost + size) in the W204 chassis. The sources were all Diamler, so not sure if they were not-in-the-know grunts or actually correct.

Third, I just have to float the statistical argument again - even if the suit alleges premature wear as the major issue in question, there are SO MANY owners driving this piss out of their cars (some in really idiotic ways) that there would have had to be more failures than the 1-10 that have been cited. Just statistics (IMHO). Not defending AMG or Mobil here, just saying that I would expect (fairly reasonably, I think) significantly more whole failures / engine issues if this was ever-present in the M156s.

Second, I've read that the new 5.5TT will simply not fit (read: cost + size) in the W204 chassis. The sources were all Diamler, so not sure if they were not-in-the-know grunts or actually correct.

MY 2013 the C63 gets the M157. I cannot state it any more plainly. Black Series variants come towards the end of a model run and there's a reason it's still a M156. As I stated things are tight up front unless they retool ($$$) and they didn't want to spend it until MY 2013. The reason MB/AMG denies it now as in Motor Trend etc is their fear they wouldn't sell any 2012s because everyone would wait on the 2013s. Not the first time this has happened.

As for the X amount of owners with no issues, the fact is 90% of owners will be clueless until they hear a ticking noise coming from under a valvecover at which point the damage has already been done. As the miles rack up the wear only gets worse.

1 in 10 AMG owners may post or read the forums, so while there's a decent cross section to look at on the net we certainly do not represent the whole pie, 90% of owners will never mod and will never read or post on the net.

FWIW gents, this isn't a debate over facts, they (the facts) have been in for over a year, you're simply seeing the culmination of data proving the issue right now. This isn't a wild delusion or a drunken guess, it is what it is, a serious design flaw that has been diagnosed and seen by enough qualified parties to allow this wholly legitimate lawsuit to be filed. In the end the customer will win if MB loses.

1 in 10 AMG owners may post or read the forums, so while there's a decent cross section to look at on the net we certainly do not represent the whole pie, 90% of owners will never mod and will never read or post on the net.

FWIW gents, this isn't a debate over facts, they (the facts) have been in for over a year, you're simply seeing the culmination of data proving the issue right now. This isn't a wild delusion or a drunken guess, it is what it is, a serious design flaw that has been diagnosed and seen by enough qualified parties to allow this wholly legitimate lawsuit to be filed. In the end the customer will win if MB loses.

I guess the true test is the number of people that join the lawsuit, that have had similar problems as Mr. Chan.

With all due respect, you do not know if this is frivolous. Once again, Mercedes has committed to this matter internally essentially verifying it exists. If this goes through successfully, it benefits you and all M156 owners.

I'm rooting for this plaintiff because paragraphs "4" and "5" under "N" (Damages and Prayer) would help us M156ers.

Just an FYI. I'll likely pick up a 2012 C63 with M156 so I can again own one of the baddest N/A production V8s in the history of the world. It may have it's flaws (all motors due though not to the extent these do) but to me it's also the ultimate V8. Killer 4v heads, great intake manifold and the bore and displacement to not only twist but torque as well.

I wanted to rep you for this post but it said I had to spread the love around. Anyway, "1 out of 1 members liked this post."

I'm on vacation now, driving a shi*ty rental. I don't want to leave this beautiful island, but I can't wait to get home and smash on my M156. Such a killer engine.

Why wouldn't all M156 motor's be effected? Given enough miles, wouldn't all of them suffer the same fate?

They all are affected. They are all wearing prematurely. If that's not affected, I don't know what is.

Originally Posted by M3_WC

I guess the true test is the number of people that join the lawsuit, that have had similar problems as Mr. Chan.

Nobody else with have to "join" the lawsuit. That's not how Class Actions work. There are two types of classes. An opt-in class and an opt-out class. In an opt-in class, potential class members receive notice and have to respond in order to participate. In an opt-out class, everyone who is affected is automatically a member and receives notice. They have to respond in order to not participate. The Plaintiff's counsel will argue for opt-out, while Defense counsel will argue for opt-in. It's really the same result in the end.

Originally Posted by Sonny

I'm rooting for this plaintiff because paragraphs "4" and "5" under "N" (Damages and Prayer) would help us M156ers.

All M156 owners will be class members, so yes, if this is successful, everyone benefits. That's the point.